Shell was at pains to keep the construction of the world’s largest floating structure under complete lockdown while its huge Prelude FLNG was being built at Samsung Heavy Industries in South Korea.

But after a speedy 27-day, 3,200-nautical- mile (5,900km) tow by three specialist tugs, with a fourth as escort and a support vessel for a scheduled en-route crew change and refuelling, the 600,000-tonne unit is now on location 475km north-northeast of Broome in Western Australia.